Heretofore, a genetic testing system (Cobas TaqMan Auto) which performs a measurement step including nucleic acid extraction in a fully automated manner is provided by Roche, Inc. (see NPL 1). This system is configured such that when a operator dispenses a sample (serum or plasma) into a sample container for exclusive use, sets the container in the system, and gives a command to start a test to the system, the system quantitatively measures the presence or absence of a virus or the like in the sample in a fully automated manner using a real time PCR (Polymerase Chain Reaction) method.
Also from Abbott, Inc., a fully automated genetic testing system (m2000p) is provided (see NPL 2). This system is configured such that when a operator sets a blood collection tube in the system and gives a command to start a test to the system, the system performs procedures from nucleic acid extraction to preparation of a measurement reaction solution in a fully automated manner. Subsequently, when the operator sets the prepared measurement reaction solution in a measurement system for exclusive use and gives a command to start a quantitative determination to the measurement system, the measurement system performs quantitative measurement by a real time PCR method.
These systems can perform all the steps in a fully automated manner, and therefore can reduce the burden on a operator.
Incidentally, from Roche, Inc., also a semi-automated testing system (Cobas Amplicor) which does not include an extraction function shown in NPL 1 is provided. This system is configured such that when a operator extracts nucleic acids by manual and installs a purified nucleic acid sample in the system, the system performs a qualitative test by a PCR method. This system does not include an extraction function, but can receive a nucleic acid sample extracted by manual, and therefore can be applied to a wide range of testing items.
Further, among conventional systems, there are also genetic testing systems (for example, EasyQ (BioMerieuex, Inc.) and ABI 7500 system (Life Technologies, Inc.)), which do not include an extraction function and a preparation function, and perform only measurement. Such a system is configured such that when a operator performs nucleic acid extraction and preparation of a reagent and a reaction solution by manual and sets the prepared measurement reaction solution in the measurement system, the system performs only a real time measurement. In the case of using such a system, since the preparation of a reagent is performed by manual, a wide range of reagent preparation methods can be applied, and thus, various testing items can be mounted.
On the other hand, a quantitative assay for nucleic acids in a sample in a genetic test differs depending on a nucleic acid amplification assay. For example, in the case of using a real time PCR method as the nucleic acid amplification assay, multiple concentration series of quantitative standard samples having known concentrations (hereinafter referred to as “standard series”) are measured by a real time PCR method and a calibration curve is created from the measurement results (Ct values) of the quantitative standard samples in advance, and at the time of measurement of a sample having an unknown concentration, the concentration is quantitatively determined by fitting the result of the measured Ct value to the created calibration curve.
Here, the quantitative standard sample includes a quantitative standard sample in which a nucleic acid having a target sequence is mixed in serum or plasma (hereinafter referred to as “quantitative standard sample before extraction”) and a purified nucleic acid prepared so as to contain a purified (pseudo) viral nucleic acid at a given concentration (hereinafter referred to as “purified quantitative standard sample”).
For reference, in FIGS. 1-1 to 1-3, concepts of the concentration measurement operations in the respective conventional systems described above are shown. FIG. 1-1 shows a concept of processing of a fully automated testing system, FIG. 1-2 shows a concept of processing of a semi-automated testing system, and FIG. 1-3 shows a concept of processing of a measurement system. As shown in FIGS. 1-1 to 1-3, it is found that a sample to be set in the system and a database to be prepared for the system differ depending on the type of the testing system. In particular, for a test which differs in an extraction method, it is necessary to individually provide a quantitative standard sample according to the extraction method. It is because when the extraction method differs, a Ct value to be measured also differs, and therefore, a standard series having a concentration series according to the extraction method is needed. Further, in the case of using an isothermal amplification assay as the nucleic acid amplification assay, a method in which an amplification curve is measured over time in the same manner as a real time PCR method, and an amplification rising time is employed is generally used. That is, multiple samples having known concentrations are prepared as quantitative standard samples, and measurement of the samples is performed in advance, whereby a calibration curve is created, and an amplification rising time of a test sample is fitted to the calibration curve, whereby a sample concentration is determined.